Understanding prion strains

We are all familiar with the idea that infectious agents such as bacteria and viruses come in different types or “strains”. It is usually easy in the laboratory to identify the strain causing an outbreak, as each strain will have differences in its genetic material. Take the example of an outbreak of food poisoning. Public health doctors can isolate the germ and strain type it and then try to identify the common source from which people became infected. Although prions do not carry genetic material, they also come in several different forms - again known as strains. If prions are just proteins, how can they come in different strains? This has been a very important question. It is now clear that there is not just one rogue form of PrP that causes prion disease but there several distinct rogue forms.

Dr Jonathan Wadsworth and his team are aiming to achieve a fundamental understanding of the biochemical differences between prion strains. This is also of key importance in understanding how prions jump from one species to another. It turns out that the species barrier does not just depend on the species concerned but also on which strain of prion is involved. For example, classical CJD prions from MM patients do not readily infect laboratory mice but vCJD prions, also from MM patients, do.